At least seven elderly people have died from heatstroke in the last two days, including a 59-year-old man found dead in his living room in a city near Tokyo on Thursday.

The energy market is watching the weather closely this summer after a strong earthquake last month damaged and closed a nuclear reactor — the world’s largest — that supplies most of the electricity to the Tokyo region.

Tokyo Electric Power Co. (TEPCO), the operator of the Kashiwazaki-Kariwa plant in Niigata prefecture, has said it may struggle to meet peak power demand from the capital if temperatures go above 35.3 Celsius, as they have done for the last few days.

The summer heat and humidity result in greater use of air conditioners, boosting electricity demand.

TEPCO increased overall power supply on Thursday by accepting help from other utilities and raising its own output as consumption was expected to rise along with temperatures, a company official said.

TEPCO raised supply to 60.10 million kilowatts by 0200 GMT on Thursday (10 p.m. EDT on Wednesday), from an original plan to supply 58.80 million kilowatts earlier in the day.

“After taking those measures, we were able to raise supply by 1.3 million kilowatts,” the official said.

TEPCO has asked six utilities to supply electricity to help fill an anticipated shortage due to the nuclear shutdown.

As of 0400-0500 GMT, electricity demand peaked at 55.94 million kilowatts, against Thursday’s peak forecast demand of 57.50 million kilowatts.

On Wednesday, peak power demand was 51.89 million kilowatts.

“We are looking at the situation closely, but I think we’ll have enough supplies,” the official said.